1. Field of the Invention
The present invention relates to a sensor response time acceleration method and apparatus, and more particularly to a sensor response time acceleration method and apparatus applied to a work machine.
2. Description of the Related Art
Work machines, such as agricultural and construction equipment utilize internal combustion engines. The internal combustion engine utilizes a variety of sensors that provide information to a controller that is used to control the operating attributes of the engine. Information from the sensors should ideally reflect the condition that the sensor is measuring. In order for this to be the case the sensor needs to respond immediately to the changes so that the environmental attribute being sensed by the sensor is reported to the controller immediately. However, in reality sensors do take a period of time to adapt to the environmental change so there is an inherent slow response in the information being supplied to controller when operating conditions of the internal combustion engine change.
Sensors, such as temperature sensors, oxygen (O2) sensors and nitrous oxide (NOX) sensors and the like have a notable slow response as compared to the response of a control system that changes the engine's operating parameters. The slow response is an inherent trait in these sensors, for example, if a temperature sensor is moved from ice water to boiling water the sensor output will not immediately change to reflect the current environment but will change over time. The change in the output can be expressed as a function of a differential equation that describes the heat transfer process of conduction of heat to or from the temperature sensor.
A problem with the slow response time of sensors is that control algorithms function based upon the reading of the sensor, which may be a reading of a historical attribute, and not the current attribute being encountered by the sensor. It is desirable to improve the speed at which information from sensors is available so that the changes in the conditions to which they are exposed can be responded to in a timelier manner and to provide a more accurate picture of the measured attribute to the controller. Such a device would provide a greater ability to control the functions of the internal combustion engine, particularly those that need fast responses.
Some techniques that attempt to improve the response time of sensors use a system looking at the change of temperature over a unit of time to predict the temperature. The disadvantage of these prior art methods is that they amplify the noise of the temperature sensor signal resulting in inaccurate assumptions about the environmental attribute.
What is needed in the art is a way to accelerate the response of sensors without introducing unwanted noise so that the environment in which the sensor is operating can rapidly be assessed so that an engine control can quickly respond to the changes to the environmental attribute.